1. Field of the Invention
The present invention relates to database management systems and, more particularly, to a system and methodology for managing data backup of an in-memory database fully integrated in a traditional disk-resident database management system.
2. Background Art
Computers are very powerful tools for storing and providing access to vast amounts of information. Computer databases are a common mechanism for storing information on computer systems while providing easy access to users. A typical database is an organized collection of related information stored as “records” having “fields” of information. As an example, a database of employees may have a record for each employee where each record contains fields designating specifics about the employee, such as name, home address, salary, and the like.
Between the actual physical database itself (i.e., the data actually stored on a storage device) and the users of the system, a database management system or DBMS is typically provided as a software cushion or layer. In essence, the DBMS shields the database user from knowing or even caring about the underlying hardware-level details. Typically, all requests from users for access to the data are processed by the DBMS. For example, information may be added or removed from data files, information retrieved from or updated in such files, and so forth, all without user knowledge of the underlying system implementation. In this manner, the DBMS provides users with a conceptual view of the database that is removed from the hardware level. The general construction and operation of database management systems is well known in the art. See e.g., Date, C., “An Introduction to Database Systems, Seventh Edition”, Part I (especially Chapters 1-4), Addison Wesley, 2000.
Of concern for robust operations with a database is the ability to achieve data backup. Database management systems typically include archive functionality enabling a user to save the data from the database to an archive system or device, such as tape. The archive can be used to restore the database (e.g., in the event the database is corrupted or damaged). This archive functionality can also be used for purposes of migrating a database from a first or “source” machine to a second or “target” machine (e.g., in the event the user wants to change the machine on which the database is used). An example of data backup operations for disk-based databases is provided in U.S. Pat. No. 5,671,350, assigned to assignee of the present invention.
In operation, a DBMS frequently needs to retrieve data from or persist data to storage devices such as disks, such as during backup operations. Unfortunately, access to disk-based storage devices can be somewhat slow. In general, support of faster database performance by the running of an entire database fully in-memory (e.g., RAM) without any on-disk storage and integrated tightly with the Database Server engine is considered desirable. Some software components, such as SolidDB from IBM Corporation (Armonk, N.Y.) or TimesTen from Oracle Corporation (Redwood City, Calif.), are available to provide some level of support of an in-memory database as stand-alone products operating as an add-on to the operations of the Database Server. However, while potentially achieving better database performance, a need remains for a backup solution for in-memory databases.
The present invention provides a solution for these and other needs.